Implantable stimulation devices deliver electrical stimuli to nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and Deep Brain Stimulators (DBS) to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder subluxation, etc. The description that follows will generally focus on the use of the invention within a Deep Brain Stimulation (DBS) system. However, the present invention may find applicability with any Implantable Pulse Generator (IPG) or in any IPG system.
As shown in FIG. 1, a DBS system includes an Implantable Pulse Generator (IPG) 10, which includes a biocompatible device case 12 comprising titanium for example. The case 12 typically holds circuitry and a battery (not shown), which battery may be either rechargeable or primary in nature. The IPG 10 is coupled to electrodes 16 via one or more electrode leads 18 (two of which are shown). The proximal ends of the leads 18 include electrode terminals 20 that are coupled to the IPG 10 at one or more connector blocks 22 fixed in a header 24, which can comprise an epoxy for example. Contacts in the connector blocks 22 make contact with the electrode terminals 20, and communicate with the circuitry inside the case 12 via feedthrough pins 26 passing through a hermetic feedthrough 28 to allow such circuitry to provide stimulation to or monitor the various electrodes 16.
In a DBS application, as is useful in the treatment of Parkinson's disease for example, the IPG 10 is typically implanted under the patient's clavicle (collarbone), and the leads 18 with electrodes 16 are implanted through holes drilled in the skull in the left and right and side of the patient's brain 32, as shown in FIG. 2. Specifically, the electrodes 16 may be implanted in the subthalamic nucleus (STN), the pedunculopontine nucleus (PPN), the Global Pallidus Interna (GPI), and/or the Ventral Intermediate Nucleus (VIM). In this regard, four leads 18 may be necessary for full coverage, as discussed further in U.S. Patent Application Publication 2013/0184794. Thereafter, a tunnel is formed under the patient's skin and fascia (e.g., over the skull, behind the patient's ear, down the neck) to connect the proximal ends of the leads 18 to the IPG 10. As the distance from the skull holes to the IPG 10 is rather long, extender leads 28 may be employed having receptacles 30 into which the electrode terminals 20 of the leads 18 can be inserted. The extender leads 28 have their own electrode terminals (not shown) to allow connection to the connector blocks 22 in the IPG 10.
While DBS therapy employed in the manner shown can provide effective neurostimulation therapy for a patient, the inventor sees room for improvement. For one, the extended distance between the IPG electronics (under the clavicle) and the site of therapy (the brain, near the top of the head) is inconvenient, as it requires a long tunnel through the patient. Further, if extender leads 28 are used, the possibility of a poor electrical connection between the electrode terminals 20 on the leads 18 and the receptacles 30 of the extender leads 28 can result in the disruption of neurostimulation therapy. Such concerns have caused the inventor to think of new solutions for implementing DBS therapy, and such solutions are disclosed herein.